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MM: Fachverband Metall- und Materialphysik

MM 38: Topical Session Diffussionless Transformations I

MM 38.4: Vortrag

Donnerstag, 17. März 2011, 15:00–15:15, IFW D

Modelling Bain path and adaptive martensite in Fe-based magnetic shape memory alloys — •Markus Ernst Gruner¹, Sandra Weiß², Sebastian Fähler², Ludwig Schultz², and Peter Entel¹ — ¹Faculty of Physics, University of Duisburg-Essen, 47048 Duisburg — ²IFW Dresden, P.O. Box 270116, 01171 Dresden

Magnetic shape memory (MSM) exhibit macroscopic strains of several percent in realistic magnetic fields. Apart from the prototypical system Ni-Mn-Ga also Fe-based alloys as fct Fe₇₀Pd₃₀ are considered for technological applications. Within this contribution we investigate the ground state behavior and finite temperature magnetism of MSM Fe-Pd alloys by means of large scale density functional theory calculations with up to 500 atoms including atomic relaxations, which are essential for an accurate description of structural properties [1]. On the essentially flat binding surface the ground state is found to be bct, while for tetragonal distortions beyond fcc an adaptive structure consisting of bct building blocks effectively decreases the energy. Also, magnetic excitations are capable of substantially altering the binding surface. The results agree closely with experimental evidence obtained from strained Fe-Pd MSM alloys epitaxially grown on different substrates, which cover the Bain path [2] and beyond confirming that adaptive structures can be deliberately grown in Fe-based MSM films.

This work is supported by the DFG through SPP 1239 and the supercomputing resources of the NIC, FZ Jülich.
M. E. Gruner, MRS Symp. Proc. 1200E, 1200-G04-04 (2010)
J. Buschbeck et al., Phys. Rev. Lett. 103, 216101 (2009)